β相处理时冷却速率对Zr-4合金耐疖状腐蚀性能的影响

Effect of β Phase Cooling Rate on Nodular Corrosion Resistance of Zircaloy-4

摘要:

利用静态高压釜腐蚀实验研究了β相处理时冷却速率对Zr-4合金板状样品在500 ℃/10.3 MPa过热蒸汽中耐疖状腐蚀性能的影响。结果表明：β相处理时，随着冷却速率的降低，Zr(Fe,Cr)2第二相会明显沿α-Zr板条晶界上析出，降低了过饱和固溶在α-Zr中的Fe和Cr含量，使得样品经过冷轧和再结晶退火后的耐疖状腐蚀性能变差。对比研究了工业生产中Zr-4合金板材耐疖状腐蚀性能不均匀的样品，认为出现这种现象与板坯在进行β相淬火时，由于尺寸较大，各处的冷却速率不均匀有关。 关键词: Zr-4；β相热处理；显微组织；耐疖状腐蚀性能

Abstract:

The effect of cooling rate after β phase heat treatment on the nodular corrosion resistance of Zircaloy-4 specimens was investigated by autoclave tests in superheated steam at 500 ℃/10.3 MPa. The nonuniform nodular corrosion resistance of Zircaloy-4 plates produced in factory was also studied. The results indicate that, the precipitation of Zr(Fe,Cr)2 second phase particles along α-Zr grain boundaries occurred with the decrease of cooling rate after β phase heating. It means that supersaturated solid solution contents of Fe and Cr alloying elements in α-Zr matrix were reduced with the decrease of cooling rate after β phase heating, and the nodular corrosion resistance of Zircaloy-4 specimens after cold rolling and recrystallization annealing was also degraded. It is considered that the variance of cooling rate at different parts of the same slab during β phase quenching in industrial production was contributed to the nonuniform nodular corrosion resistance of Zircaloy-4 plates.